1. Field of the Invention.
The present invention pertains to gate valves or slot valves of the type used in vacuum contained automated substrate handling systems, such as may commonly be employed in modular robotic wafer fabricating systems.
2. Related Art
In the semiconductor industry, automated silicon wafer substrate handling systems are utilized to move wafers into and out of process modules that perform various operations on the wafers, such as vapor deposition, ionization, etching, etc. These handling systems are commonly referred to as cluster tools, and an example of such a system is the Marathon Series cluster platforms available from Brooks Automation, Lowell, Mass., USA.
The processes performed on the wafers are done within vacuum chambers, and the cluster platforms and associated equipment are housed in "clean" rooms, the environments of which are strictly controlled. Vacuum chambers and clean rooms are utilized in order to prevent the smallest of particles from being introduced into the wafer matrices In addition, the wafer processing equipment of cluster tools is designed for low particulate generation through millions of cycles of operation. To achieve ultrapure fabrication techniques, processing equipment is employed that has a minimum of moving parts, and to further prevent particle contamination, machine componentry is properly isolated and sealed.
With clean rooms, space utilization is of utmost importance, as the costs for operating a clean room are extremely expensive. Accordingly, there is an advantage in providing more efficient equipment in less space, in order to lower manufacturing costs.
Gate valves (or slot valves) are commonly employed to provide vacuum seals at numerous locations between modular integrated processing equipment. For example, gate valves are positioned between wafer cassette modules and central handling modules, and between central handling modules and process modules. Gate valves open to allow transfer of wafers between modules, and close to seal off modules so that vacuum controlled processes may be performed within the modules.
Present gate valve assemblies include generally a gate valve housing and an actuator housing with associated controls. While these gate valve designs provide narrow profiles, allowing closely adjacent positioning of cooperating modules, the height of such gate valve assemblies can be extensive, which causes space utilization concerns below the processing equipment where associated controls and pumps are positioned. Accordingly, advantages can be achieved in space utilization by reducing the size of all processing and handling equipment, particularly gate valves. The action from components of the present valve are confined within a housing having a height considerably less than conventional actuating systems. This is accomplished, in part, by confining actuating elements within the housing.